The present application relates to semiconductors, and more specifically, to techniques for forming semiconductor structures. As memory density increases, the need for new memory technology other than dynamic random access memory (DRAM) is needed. DRAM technology scaling is facing a wall due to various problems such as retention time. Emerging memory devices store data as resistance values. For example, phase change memory (PCM), magnetic random access memory (MRAM), spin-torque-transfer magnetic random access memory (STT-MRAM), and resistive random access memory (ReRAM or RRAM) use variations of resistance values to store data.